John b



(No Model.) Y

J. E. DANN & J. LAPP.

' TELEPHONE RECEIVER.

No. 338,491. Patentd Mar. 23, 1886.

UNITED STATES JOHN E. DANN AND JOHN LAPP,

PATENT OFFICE.

OF HONEOYE FALLS, NEW YORK.

TELEPHONE-RECEIVER.

SPEGIFICATIUN forming part of Letters Patent No. 338,491, dated March23, 1886.

Application filed October 31, 1885. Serial No. 181,531. (No model.)

To all whom it may concern.-

Be it known that we, JOHN E. DANN and JOHN LAII, of Honeoye Falls, inthe county of Monroe and State of New York, have in- Vented a new anduseful Improvement in Telephonic Receivers, of which the following is adescription.

Our invention is an improvement in telephonic receivers of the Rois type-that is to say, such as depend for their operation upon the coactionof an electromagnet and an armature arranged in front of it, and whosevibrations are synchronous with those of the diaphragm of thetransmitting-instrument. It is more particularly an improvement uponreceivers whose diaphragm is connected by a rigid rod with the armatureof an electro magnet which is in the line-circuit. lVe employ twohorseshoe electric magnets arranged opposite each other-i. 6.,respectively right and left from the diaphragm, and on the rear side ofthe same-and we connect both armatures of said magnets with thediaphragm by rigid rods, so that both shall simultaneously act on thelatter to vibrate it as forcibly as possible. We have found byexperiment that this arrangement produces a very marked eifect inloudness of tone, and a better one than can be secured by employing asingle magnet of double the size of one of ours. The improvement isdoubtless attributable mainly to this cause-namely, the and poles ofeach magnet react on each other and intensify their respectivepolarities, and the same is true of the polarities induced in eacharmature, so that the force of the our rent is converted into a strongmagnetic attraction that acts powerfully on the diaphragm. Someimportance may also be attached to the effect of two armatures acting atonce, since they mechanically neutralize each other in so far as theywould tend, if acting separately, to distort the diaphragm by reason ofmoving in an arc and not in a plane at right angles to the same.

Figure l is a perspective view of our receiving-instrument, the back orcover being detached. Fig. 2 is a rear elevation of the same, thearmature being removed. Fig. 3 is a cross-section through :0 at, Fig. 1.Fig. 4 is The letter A indicates the body of the re ceiving-instrument.

The diaphragm B is arranged as usual in telephonic receivers, and may bemade of metal, membrane, or other suitable material. Laterally from thediaphragm are arranged two horseshoe magnets, O O-one on each sidetheirfeet pointing backward. The flat bar armatures D D of said magnets haverigid horiz'ontal arms a, which project toward each other, so that theirfree ends nearly meet at a point directly opposite the center of thediaphragm B, with which they are connected by means of small but rigidrods E. The latter are in this instance soldered to the diaphragm, itbeing of metal,- but when made of membrane it is obvious that some othersuitable means of connection will be necessary. Short rigid arms b I)also project backward from the armatures D D, and have points 6, thatrest in sockets in the heads of screws d. The latter serve as adjustablebearings or supports for the armatures,by which their proximity to themagnets (which they are never in actual contact with) may be easilyregulated at will. In place of these screws, various devices forisupporting and holding the ends of arms I) b may be employed. It willbe seen that the armatures have thus two points of support-namely, thediaphragm and the screws; but they are held attracted by magnets whosecores are polarized, so that the diaphragm is thereby pressed outward orheld under tension to a degree cor responding to the constant attractiveforce of the magnets. In place of the latter being of the permanenttype,we may employ soft-iron cores energized by a local circuit; but theformer arrangement is the more economical.

To supplement the action of the polarized magnets cores on thearmatures, and to better hold them in due position, they are providedwith plate springs f, extending rearward, and whose free ends are heldunder a pivoted catch, 9, or other suitable device. It will be notedthat the point of contact of such springs and catches is in alignmentboth ways with the heads of screws, which local relation is essential tovibration of the armatures with the least friction and greatest freedomand ac I curacy.

The connection with the line-wire w is from binding-post 1, Fig. 2, tothe center of the coil around the adjacent leg of the nearer magnet, andfrom the outer coil of such leg to the center of the coil on the other1eg,thence to the opposite magnet, and then to the other binding-post,2. It will be apparent from this arrangement that both magnets areenergized simultaneously by the line-current, and simultaneouslydemagnetized more or less when the circuit is less ened, (save of coursethe constant attraction proceeding from polarized cores.) Both armaturesare therefore attracted and released at the same instant, so that theirpush-rods E act together on the diaphragm B, throwing it into vibrationscorresponding to the impulses of the current, and efl'ecting the desiredtransmission of sound loudly and accurately.

What We claim is- 1. In a telephonic receiver, the combination, with thediaphragm B, of the two horseshoe electro-magnets O and 0, arranged onthe rear side of and in laterally-opposite directions from thediaphragm, the two armatures D D, having arms a projecting toward eachother, and the two rigid rods EE, connecting these arms with the centerof the diaphragm, as shown and described, for the purpose specified.

2. In a telephonic receiving-instrument, the combination of thesocketscrews with the armature-arms having points that constitutebearings or fulcra for said armatures, as shown and described.

J OHN E. DANN. JOHN LAPP. Witnesses:

AMos XV. HART, SoLoN O. KEMON.

